Age-related shifts in the diet composition of southern elephant seals expand overall foraging niche

By I. Field, Corey J. A. Bradshaw, J. Hoff, H. Burton, Mark A. Hindell. 2007

88 citations recorded by the source corpus.

Southern elephant seals are important apex predators in a highly variable and unpredictable marine environment. In the presence of resource limitation, foraging behaviours evolve to reduce intra-specific competition increasing a species’ overall probability of successful foraging. We examined the diet of 141 (aged 1–3 years) juvenile southern elephant seals to test the hypotheses that differences between ages, sexes and seasons in diet structure occur. We described prey species composition for common squid and fish species and the mean size of cephalopod prey items for these age groups. Three cephalopod species dominated the stomach samples, Alluroteuthis antarcticus, Histioteuthis eltaninae and Slosarczykovia circumantarcticus. We found age-related differences in both species composition and size of larger prey species that probably relate to ontogenetic changes in diving ability and haul-out behaviour and prey availability. These changes in foraging behaviour and diet are hypothesised to reduce intra-specific food competition concomitant with the increase in foraging niche of growing juveniles.

Subfields: Ecology, Ecology, Evolution, Behavior and Systematics, Global and Planetary Change

View Paper: https://www.semanticscholar.org/paper/c668fc76b9ad8ae82fded345a24bfc3d63867e8d

How researchers see this paper

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In Ecology

1. Bj Godley
2. AC Broderick
3. Y. Cherel
4. Daniel P. Costa
5. P. Richard
6. Michael S. Coyne
7. A. Rees
8. C. Guinet

In Ecology, Evolution, Behavior and Systematics

1. Bj Godley
2. AC Broderick
3. P. Richard
4. Camille Fontaine
5. Y. Cherel
6. C. Werner
7. Daniel P. Costa
8. F. Trillmich

In Global and Planetary Change

1. Bj Godley
2. AC Broderick
3. Michael S. Coyne
4. A. Rees
5. Y. Cherel
6. P. Richard
7. Daniel P. Costa
8. C. Guinet

Citations in the corpus

• Linking foraging behaviour to physical oceanographic structures: Southern elephant seals and mesoscale eddies east of Kerguelen Islands (2010, background): “Variations in foraging-searching behaviour and /or differences in prey selection (Field et al., 2004, 2007a) could explain this inter-individual variability that generates the observed population plasticity.”
• Age, body mass and environmental variation shape the foraging ontogeny of Galapagos sea lions (2012, background): “A similar trade-off in favour of increased foraging time was found in ASL juveniles (Fowler et al. 2006).”
• Stable isotopes reveal the trophic position and mesopelagic fish diet of female southern elephant seals breeding on the Kerguelen Islands (2008, methodology): “Finally, we estimated the trophic level (TL) of elephant seals using their δ15N values and compared it with those of other consumers to verify the common assumption that marine mammals are top predators in marine ecosystems (Bradshaw et al. 2003, Field et al. 2007).”
• Behavioural polymorphism in one of the world’s largest populations of loggerhead sea turtles Caretta caretta (2010, background): “Many megavertebrate taxa utilise large expanses of the marine environment, with differential spatial use according to life stage (e.g. tuna: Dickhut et al. 2009; albatrosses: Croxall et al. 2005; penguins: Jouventin et al. 1994; seals: Field et al. 2005, 2007; whales: Zerbini et al. 2006).”